net/tipc/subscr.c

   1 /*
   2  * net/tipc/subscr.c: TIPC network topology service
   3  *
   4  * Copyright (c) 2000-2006, Ericsson AB
   5  * Copyright (c) 2005-2007, Wind River Systems
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the names of the copyright holders nor the names of its
  17  *    contributors may be used to endorse or promote products derived from
  18  *    this software without specific prior written permission.
  19  *
  20  * Alternatively, this software may be distributed under the terms of the
  21  * GNU General Public License ("GPL") version 2 as published by the Free
  22  * Software Foundation.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  25  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  28  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  29  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  30  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  31  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  32  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  33  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  34  * POSSIBILITY OF SUCH DAMAGE.
  35  */
  36
  37 #include "core.h"
  38 #include "dbg.h"
  39 #include "name_table.h"
  40 #include "port.h"
  41 #include "ref.h"
  42 #include "subscr.h"
  43
  44 /**
  45  * struct subscriber - TIPC network topology subscriber
  46  * @port_ref: object reference to server port connecting to subscriber
  47  * @lock: pointer to spinlock controlling access to subscriber's server port
  48  * @subscriber_list: adjacent subscribers in top. server's list of subscribers
  49  * @subscription_list: list of subscription objects for this subscriber
  50  */
  51
  52 struct subscriber {
  53         u32 port_ref;
  54         spinlock_t *lock;
  55         struct list_head subscriber_list;
  56         struct list_head subscription_list;
  57 };
  58
  59 /**
  60  * struct top_srv - TIPC network topology subscription service
  61  * @user_ref: TIPC userid of subscription service
  62  * @setup_port: reference to TIPC port that handles subscription requests
  63  * @subscription_count: number of active subscriptions (not subscribers!)
  64  * @subscriber_list: list of ports subscribing to service
  65  * @lock: spinlock govering access to subscriber list
  66  */
  67
  68 struct top_srv {
  69         u32 user_ref;
  70         u32 setup_port;
  71         atomic_t subscription_count;
  72         struct list_head subscriber_list;
  73         spinlock_t lock;
  74 };
  75
  76 static struct top_srv topsrv = { 0 };
  77
  78 /**
  79  * subscr_send_event - send a message containing a tipc_event to the subscriber
  80  *
  81  * Note: Must not hold subscriber's server port lock, since tipc_send() will
  82  *       try to take the lock if the message is rejected and returned!
  83  */
  84
  85 static void subscr_send_event(struct subscription *sub,
  86                               u32 found_lower,
  87                               u32 found_upper,
  88                               u32 event,
  89                               u32 port_ref,
  90                               u32 node)
  91 {
  92         struct iovec msg_sect;
  93
  94         msg_sect.iov_base = (void *)&sub->evt;
  95         msg_sect.iov_len = sizeof(struct tipc_event);
  96
  97         sub->evt.event = htonl(event);
  98         sub->evt.found_lower = htonl(found_lower);
  99         sub->evt.found_upper = htonl(found_upper);
 100         sub->evt.port.ref = htonl(port_ref);
 101         sub->evt.port.node = htonl(node);
 102         tipc_send(sub->server_ref, 1, &msg_sect);
 103 }
 104
 105 /**
 106  * tipc_subscr_overlap - test for subscription overlap with the given values
 107  *
 108  * Returns 1 if there is overlap, otherwise 0.
 109  */
 110
 111 int tipc_subscr_overlap(struct subscription *sub,
 112                         u32 found_lower,
 113                         u32 found_upper)
 114
 115 {
 116         if (found_lower < sub->seq.lower)
 117                 found_lower = sub->seq.lower;
 118         if (found_upper > sub->seq.upper)
 119                 found_upper = sub->seq.upper;
 120         if (found_lower > found_upper)
 121                 return 0;
 122         return 1;
 123 }
 124
 125 /**
 126  * tipc_subscr_report_overlap - issue event if there is subscription overlap
 127  *
 128  * Protected by nameseq.lock in name_table.c
 129  */
 130
 131 void tipc_subscr_report_overlap(struct subscription *sub,
 132                                 u32 found_lower,
 133                                 u32 found_upper,
 134                                 u32 event,
 135                                 u32 port_ref,
 136                                 u32 node,
 137                                 int must)
 138 {
 139         if (!tipc_subscr_overlap(sub, found_lower, found_upper))
 140                 return;
 141         if (!must && !(sub->filter & TIPC_SUB_PORTS))
 142                 return;
 143
 144         sub->event_cb(sub, found_lower, found_upper, event, port_ref, node);
 145 }
 146
 147 /**
 148  * subscr_timeout - subscription timeout has occurred
 149  */
 150
 151 static void subscr_timeout(struct subscription *sub)
 152 {
 153         struct port *server_port;
 154
 155         /* Validate server port reference (in case subscriber is terminating) */
 156
 157         server_port = tipc_port_lock(sub->server_ref);
 158         if (server_port == NULL)
 159                 return;
 160
 161         /* Validate timeout (in case subscription is being cancelled) */
 162
 163         if (sub->timeout == TIPC_WAIT_FOREVER) {
 164                 tipc_port_unlock(server_port);
 165                 return;
 166         }
 167
 168         /* Unlink subscription from name table */
 169
 170         tipc_nametbl_unsubscribe(sub);
 171
 172         /* Unlink subscription from subscriber */
 173
 174         list_del(&sub->subscription_list);
 175
 176         /* Release subscriber's server port */
 177
 178         tipc_port_unlock(server_port);
 179
 180         /* Notify subscriber of timeout */
 181
 182         subscr_send_event(sub, sub->evt.s.seq.lower, sub->evt.s.seq.upper,
 183                           TIPC_SUBSCR_TIMEOUT, 0, 0);
 184
 185         /* Now destroy subscription */
 186
 187         k_term_timer(&sub->timer);
 188         kfree(sub);
 189         atomic_dec(&topsrv.subscription_count);
 190 }
 191
 192 /**
 193  * subscr_del - delete a subscription within a subscription list
 194  *
 195  * Called with subscriber port locked.
 196  */
 197
 198 static void subscr_del(struct subscription *sub)
 199 {
 200         tipc_nametbl_unsubscribe(sub);
 201         list_del(&sub->subscription_list);
 202         kfree(sub);
 203         atomic_dec(&topsrv.subscription_count);
 204 }
 205
 206 /**
 207  * subscr_terminate - terminate communication with a subscriber
 208  *
 209  * Called with subscriber port locked.  Routine must temporarily release lock
 210  * to enable subscription timeout routine(s) to finish without deadlocking;
 211  * the lock is then reclaimed to allow caller to release it upon return.
 212  * (This should work even in the unlikely event some other thread creates
 213  * a new object reference in the interim that uses this lock; this routine will
 214  * simply wait for it to be released, then claim it.)
 215  */
 216
 217 static void subscr_terminate(struct subscriber *subscriber)
 218 {
 219         u32 port_ref;
 220         struct subscription *sub;
 221         struct subscription *sub_temp;
 222
 223         /* Invalidate subscriber reference */
 224
 225         port_ref = subscriber->port_ref;
 226         subscriber->port_ref = 0;
 227         spin_unlock_bh(subscriber->lock);
 228
 229         /* Sever connection to subscriber */
 230
 231         tipc_shutdown(port_ref);
 232         tipc_deleteport(port_ref);
 233
 234         /* Destroy any existing subscriptions for subscriber */
 235
 236         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
 237                                  subscription_list) {
 238                 if (sub->timeout != TIPC_WAIT_FOREVER) {
 239                         k_cancel_timer(&sub->timer);
 240                         k_term_timer(&sub->timer);
 241                 }
 242                 dbg("Term: Removing sub %u,%u,%u from subscriber %x list\n",
 243                     sub->seq.type, sub->seq.lower, sub->seq.upper, subscriber);
 244                 subscr_del(sub);
 245         }
 246
 247         /* Remove subscriber from topology server's subscriber list */
 248
 249         spin_lock_bh(&topsrv.lock);
 250         list_del(&subscriber->subscriber_list);
 251         spin_unlock_bh(&topsrv.lock);
 252
 253         /* Reclaim subscriber lock */
 254
 255         spin_lock_bh(subscriber->lock);
 256
 257         /* Now destroy subscriber */
 258
 259         kfree(subscriber);
 260 }
 261
 262 /**
 263  * subscr_cancel - handle subscription cancellation request
 264  *
 265  * Called with subscriber port locked.  Routine must temporarily release lock
 266  * to enable the subscription timeout routine to finish without deadlocking;
 267  * the lock is then reclaimed to allow caller to release it upon return.
 268  *
 269  * Note that fields of 's' use subscriber's endianness!
 270  */
 271
 272 static void subscr_cancel(struct tipc_subscr *s,
 273                           struct subscriber *subscriber)
 274 {
 275         struct subscription *sub;
 276         struct subscription *sub_temp;
 277         __u32 type, lower, upper, timeout, filter;
 278         int found = 0;
 279
 280         /* Find first matching subscription, exit if not found */
 281
 282         type = ntohl(s->seq.type);
 283         lower = ntohl(s->seq.lower);
 284         upper = ntohl(s->seq.upper);
 285         timeout = ntohl(s->timeout);
 286         filter = ntohl(s->filter) & ~TIPC_SUB_CANCEL;
 287
 288         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
 289                                  subscription_list) {
 290                         if ((type == sub->seq.type) &&
 291                             (lower == sub->seq.lower) &&
 292                             (upper == sub->seq.upper) &&
 293                             (timeout == sub->timeout) &&
 294                             (filter == sub->filter) &&
 295                              !memcmp(s->usr_handle,sub->evt.s.usr_handle,
 296                                      sizeof(s->usr_handle)) ){
 297                                 found = 1;
 298                                 break;
 299                         }
 300         }
 301         if (!found)
 302                 return;
 303
 304         /* Cancel subscription timer (if used), then delete subscription */
 305
 306         if (sub->timeout != TIPC_WAIT_FOREVER) {
 307                 sub->timeout = TIPC_WAIT_FOREVER;
 308                 spin_unlock_bh(subscriber->lock);
 309                 k_cancel_timer(&sub->timer);
 310                 k_term_timer(&sub->timer);
 311                 spin_lock_bh(subscriber->lock);
 312         }
 313         dbg("Cancel: removing sub %u,%u,%u from subscriber %p list\n",
 314             sub->seq.type, sub->seq.lower, sub->seq.upper, subscriber);
 315         subscr_del(sub);
 316 }
 317
 318 /**
 319  * subscr_subscribe - create subscription for subscriber
 320  *
 321  * Called with subscriber port locked.
 322  */
 323
 324 static struct subscription *subscr_subscribe(struct tipc_subscr *s,
 325                                              struct subscriber *subscriber)
 326 {
 327         struct subscription *sub;
 328
 329         /* Detect & process a subscription cancellation request */
 330
 331         if (ntohl(s->filter) & TIPC_SUB_CANCEL) {
 332                 subscr_cancel(s, subscriber);
 333                 return NULL;
 334         }
 335
 336         /* Refuse subscription if global limit exceeded */
 337
 338         if (atomic_read(&topsrv.subscription_count) >= tipc_max_subscriptions) {
 339                 warn("Subscription rejected, subscription limit reached (%u)\n",
 340                      tipc_max_subscriptions);
 341                 subscr_terminate(subscriber);
 342                 return NULL;
 343         }
 344
 345         /* Allocate subscription object */
 346
 347         sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
 348         if (!sub) {
 349                 warn("Subscription rejected, no memory\n");
 350                 subscr_terminate(subscriber);
 351                 return NULL;
 352         }
 353
 354         /* Initialize subscription object */
 355
 356         sub->seq.type = ntohl(s->seq.type);
 357         sub->seq.lower = ntohl(s->seq.lower);
 358         sub->seq.upper = ntohl(s->seq.upper);
 359         sub->timeout = ntohl(s->timeout);
 360         sub->filter = ntohl(s->filter);
 361         if ((sub->filter && (sub->filter != TIPC_SUB_PORTS)) ||
 362             (sub->seq.lower > sub->seq.upper)) {
 363                 warn("Subscription rejected, illegal request\n");
 364                 kfree(sub);
 365                 subscr_terminate(subscriber);
 366                 return NULL;
 367         }
 368         sub->event_cb = subscr_send_event;
 369         INIT_LIST_HEAD(&sub->nameseq_list);
 370         list_add(&sub->subscription_list, &subscriber->subscription_list);
 371         sub->server_ref = subscriber->port_ref;
 372         memcpy(&sub->evt.s, s, sizeof(struct tipc_subscr));
 373         atomic_inc(&topsrv.subscription_count);
 374         if (sub->timeout != TIPC_WAIT_FOREVER) {
 375                 k_init_timer(&sub->timer,
 376                              (Handler)subscr_timeout, (unsigned long)sub);
 377                 k_start_timer(&sub->timer, sub->timeout);
 378         }
 379
 380         return sub;
 381 }
 382
 383 /**
 384  * subscr_conn_shutdown_event - handle termination request from subscriber
 385  *
 386  * Called with subscriber's server port unlocked.
 387  */
 388
 389 static void subscr_conn_shutdown_event(void *usr_handle,
 390                                        u32 port_ref,
 391                                        struct sk_buff **buf,
 392                                        unsigned char const *data,
 393                                        unsigned int size,
 394                                        int reason)
 395 {
 396         struct subscriber *subscriber = usr_handle;
 397         spinlock_t *subscriber_lock;
 398
 399         if (tipc_port_lock(port_ref) == NULL)
 400                 return;
 401
 402         subscriber_lock = subscriber->lock;
 403         subscr_terminate(subscriber);
 404         spin_unlock_bh(subscriber_lock);
 405 }
 406
 407 /**
 408  * subscr_conn_msg_event - handle new subscription request from subscriber
 409  *
 410  * Called with subscriber's server port unlocked.
 411  */
 412
 413 static void subscr_conn_msg_event(void *usr_handle,
 414                                   u32 port_ref,
 415                                   struct sk_buff **buf,
 416                                   const unchar *data,
 417                                   u32 size)
 418 {
 419         struct subscriber *subscriber = usr_handle;
 420         spinlock_t *subscriber_lock;
 421         struct subscription *sub;
 422
 423         /*
 424          * Lock subscriber's server port (& make a local copy of lock pointer,
 425          * in case subscriber is deleted while processing subscription request)
 426          */
 427
 428         if (tipc_port_lock(port_ref) == NULL)
 429                 return;
 430
 431         subscriber_lock = subscriber->lock;
 432
 433         if (size != sizeof(struct tipc_subscr)) {
 434                 subscr_terminate(subscriber);
 435                 spin_unlock_bh(subscriber_lock);
 436         } else {
 437                 sub = subscr_subscribe((struct tipc_subscr *)data, subscriber);
 438                 spin_unlock_bh(subscriber_lock);
 439                 if (sub != NULL) {
 440
 441                         /*
 442                          * We must release the server port lock before adding a
 443                          * subscription to the name table since TIPC needs to be
 444                          * able to (re)acquire the port lock if an event message
 445                          * issued by the subscription process is rejected and
 446                          * returned.  The subscription cannot be deleted while
 447                          * it is being added to the name table because:
 448                          * a) the single-threading of the native API port code
 449                          *    ensures the subscription cannot be cancelled and
 450                          *    the subscriber connection cannot be broken, and
 451                          * b) the name table lock ensures the subscription
 452                          *    timeout code cannot delete the subscription,
 453                          * so the subscription object is still protected.
 454                          */
 455
 456                         tipc_nametbl_subscribe(sub);
 457                 }
 458         }
 459 }
 460
 461 /**
 462  * subscr_named_msg_event - handle request to establish a new subscriber
 463  */
 464
 465 static void subscr_named_msg_event(void *usr_handle,
 466                                    u32 port_ref,
 467                                    struct sk_buff **buf,
 468                                    const unchar *data,
 469                                    u32 size,
 470                                    u32 importance,
 471                                    struct tipc_portid const *orig,
 472                                    struct tipc_name_seq const *dest)
 473 {
 474         static struct iovec msg_sect = {NULL, 0};
 475
 476         struct subscriber *subscriber;
 477         u32 server_port_ref;
 478
 479         /* Create subscriber object */
 480
 481         subscriber = kzalloc(sizeof(struct subscriber), GFP_ATOMIC);
 482         if (subscriber == NULL) {
 483                 warn("Subscriber rejected, no memory\n");
 484                 return;
 485         }
 486         INIT_LIST_HEAD(&subscriber->subscription_list);
 487         INIT_LIST_HEAD(&subscriber->subscriber_list);
 488
 489         /* Create server port & establish connection to subscriber */
 490
 491         tipc_createport(topsrv.user_ref,
 492                         subscriber,
 493                         importance,
 494                         NULL,
 495                         NULL,
 496                         subscr_conn_shutdown_event,
 497                         NULL,
 498                         NULL,
 499                         subscr_conn_msg_event,
 500                         NULL,
 501                         &subscriber->port_ref);
 502         if (subscriber->port_ref == 0) {
 503                 warn("Subscriber rejected, unable to create port\n");
 504                 kfree(subscriber);
 505                 return;
 506         }
 507         tipc_connect2port(subscriber->port_ref, orig);
 508
 509         /* Lock server port (& save lock address for future use) */
 510
 511         subscriber->lock = tipc_port_lock(subscriber->port_ref)->publ.lock;
 512
 513         /* Add subscriber to topology server's subscriber list */
 514
 515         spin_lock_bh(&topsrv.lock);
 516         list_add(&subscriber->subscriber_list, &topsrv.subscriber_list);
 517         spin_unlock_bh(&topsrv.lock);
 518
 519         /* Unlock server port */
 520
 521         server_port_ref = subscriber->port_ref;
 522         spin_unlock_bh(subscriber->lock);
 523
 524         /* Send an ACK- to complete connection handshaking */
 525
 526         tipc_send(server_port_ref, 1, &msg_sect);
 527
 528         /* Handle optional subscription request */
 529
 530         if (size != 0) {
 531                 subscr_conn_msg_event(subscriber, server_port_ref,
 532                                       buf, data, size);
 533         }
 534 }
 535
 536 int tipc_subscr_start(void)
 537 {
 538         struct tipc_name_seq seq = {TIPC_TOP_SRV, TIPC_TOP_SRV, TIPC_TOP_SRV};
 539         int res = -1;
 540
 541         memset(&topsrv, 0, sizeof (topsrv));
 542         spin_lock_init(&topsrv.lock);
 543         INIT_LIST_HEAD(&topsrv.subscriber_list);
 544
 545         spin_lock_bh(&topsrv.lock);
 546         res = tipc_attach(&topsrv.user_ref, NULL, NULL);
 547         if (res) {
 548                 spin_unlock_bh(&topsrv.lock);
 549                 return res;
 550         }
 551
 552         res = tipc_createport(topsrv.user_ref,
 553                               NULL,
 554                               TIPC_CRITICAL_IMPORTANCE,
 555                               NULL,
 556                               NULL,
 557                               NULL,
 558                               NULL,
 559                               subscr_named_msg_event,
 560                               NULL,
 561                               NULL,
 562                               &topsrv.setup_port);
 563         if (res)
 564                 goto failed;
 565
 566         res = tipc_nametbl_publish_rsv(topsrv.setup_port, TIPC_NODE_SCOPE, &seq);
 567         if (res)
 568                 goto failed;
 569
 570         spin_unlock_bh(&topsrv.lock);
 571         return 0;
 572
 573 failed:
 574         err("Failed to create subscription service\n");
 575         tipc_detach(topsrv.user_ref);
 576         topsrv.user_ref = 0;
 577         spin_unlock_bh(&topsrv.lock);
 578         return res;
 579 }
 580
 581 void tipc_subscr_stop(void)
 582 {
 583         struct subscriber *subscriber;
 584         struct subscriber *subscriber_temp;
 585         spinlock_t *subscriber_lock;
 586
 587         if (topsrv.user_ref) {
 588                 tipc_deleteport(topsrv.setup_port);
 589                 list_for_each_entry_safe(subscriber, subscriber_temp,
 590                                          &topsrv.subscriber_list,
 591                                          subscriber_list) {
 592                         subscriber_lock = subscriber->lock;
 593                         spin_lock_bh(subscriber_lock);
 594                         subscr_terminate(subscriber);
 595                         spin_unlock_bh(subscriber_lock);
 596                 }
 597                 tipc_detach(topsrv.user_ref);
 598                 topsrv.user_ref = 0;
 599         }
 600 }
 601
 602
 603 int tipc_ispublished(struct tipc_name const *name)
 604 {
 605         u32 domain = 0;
 606
 607         return tipc_nametbl_translate(name->type, name->instance, &domain) != 0;
 608 }
 609